///*
// * %W% %E%
// *
// * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
// * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
// */
//
//import java.util.*;
//import java.util.ArrayList;
//
///**
// * Linked list implementation of the <tt>List</tt> interface.  Implements all
// * optional list operations, and permits all elements (including
// * <tt>null</tt>).  In addition to implementing the <tt>List</tt> interface,
// * the <tt>LinkedList</tt> class provides uniformly named methods to
// * <tt>get</tt>, <tt>remove</tt> and <tt>insert</tt> an element at the
// * beginning and end of the list.  These operations allow linked lists to be
// * used as a stack, {@linkplain Queue queue}, or {@linkplain Deque
// * double-ended queue}. <p>
// *
// * The class implements the <tt>Deque</tt> interface, providing
// * first-in-first-out queue operations for <tt>add</tt>,
// * <tt>poll</tt>, along with other stack and deque operations.<p>
// *
// * All of the operations perform as could be expected for a doubly-linked
// * list.  Operations that index into the list will traverse the list from
// * the beginning or the end, whichever is closer to the specified index.<p>
// *
// * <p><strong>Note that this implementation is not synchronized.</strong>
// * If multiple threads access a linked list concurrently, and at least
// * one of the threads modifies the list structurally, it <i>must</i> be
// * synchronized externally.  (A structural modification is any operation
// * that adds or deletes one or more elements; merely setting the value of
// * an element is not a structural modification.)  This is typically
// * accomplished by synchronizing on some object that naturally
// * encapsulates the list.
// *
// * If no such object exists, the list should be "wrapped" using the
// * {@link Collections#synchronizedList Collections.synchronizedList}
// * method.  This is best done at creation time, to prevent accidental
// * unsynchronized access to the list:<pre>
// *   List list = Collections.synchronizedList(new LinkedList(...));</pre>
// *
// * <p>The iterators returned by this class's <tt>iterator</tt> and
// * <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is
// * structurally modified at any time after the iterator is created, in
// * any way except through the Iterator's own <tt>remove</tt> or
// * <tt>add</tt> methods, the iterator will throw a {@link
// * ConcurrentModificationException}.  Thus, in the face of concurrent
// * modification, the iterator fails quickly and cleanly, rather than
// * risking arbitrary, non-deterministic behavior at an undetermined
// * time in the future.
// *
// * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
// * as it is, generally speaking, impossible to make any hard guarantees in the
// * presence of unsynchronized concurrent modification.  Fail-fast iterators
// * throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
// * Therefore, it would be wrong to write a program that depended on this
// * exception for its correctness:   <i>the fail-fast behavior of iterators
// * should be used only to detect bugs.</i>
// *
// * <p>This class is a member of the
// * <a href="{@docRoot}/../technotes/guides/collections/index.html">
// * Java Collections Framework</a>.
// *
// * @author  Josh Bloch
// * @version %I%, %G%
// * @see        List
// * @see        ArrayList
// * @see	    Vector
// * @since 1.2
// * @param <E> the type of elements held in this collection
// */
//
//public class LinkedList<E>
//    extends AbstractSequentialList<E>
//    implements List<E>, Deque<E>, Cloneable, java.io.Serializable
//{
//    private transient Entry<E> header = new Entry<E>(null, null, null);
//    private transient int size = 0;
//
//    /**
//     * Constructs an empty list.
//     */
//    public LinkedList() {
//        header.next = header.previous = header;
//    }
//
//    /**
//     * Constructs a list containing the elements of the specified
//     * collection, in the order they are returned by the collection's
//     * iterator.
//     *
//     * @param  c the collection whose elements are to be placed into this list
//     * @throws NullPointerException if the specified collection is null
//     */
//    public LinkedList(Collection<? extends E> c) {
//	this();
//	addAll(c);
//    }
//
//    /**
//     * Returns the first element in this list.
//     *
//     * @return the first element in this list
//     * @throws NoSuchElementException if this list is empty
//     */
//    public E getFirst() {
//	if (size==0)
//	    throw new NoSuchElementException();
//
//	return header.next.element;
//    }
//
//    /**
//     * Returns the last element in this list.
//     *
//     * @return the last element in this list
//     * @throws NoSuchElementException if this list is empty
//     */
//    public E getLast()  {
//	if (size==0)
//	    throw new NoSuchElementException();
//
//	return header.previous.element;
//    }
//
//    /**
//     * Removes and returns the first element from this list.
//     *
//     * @return the first element from this list
//     * @throws NoSuchElementException if this list is empty
//     */
//    public E removeFirst() {
//	return remove(header.next);
//    }
//
//    /**
//     * Removes and returns the last element from this list.
//     *
//     * @return the last element from this list
//     * @throws NoSuchElementException if this list is empty
//     */
//    public E removeLast() {
//	return remove(header.previous);
//    }
//
//    /**
//     * Inserts the specified element at the beginning of this list.
//     *
//     * @param e the element to add
//     */
//    public void addFirst(E e) {
//	addBefore(e, header.next);
//    }
//
//    /**
//     * Appends the specified element to the end of this list.
//     *
//     * <p>This method is equivalent to {@link #add}.
//     *
//     * @param e the element to add
//     */
//    public void addLast(E e) {
//	addBefore(e, header);
//    }
//
//    /**
//     * Returns <tt>true</tt> if this list contains the specified element.
//     * More formally, returns <tt>true</tt> if and only if this list contains
//     * at least one element <tt>e</tt> such that
//     * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>.
//     *
//     * @param o element whose presence in this list is to be tested
//     * @return <tt>true</tt> if this list contains the specified element
//     */
//    public boolean contains(Object o) {
//        return indexOf(o) != -1;
//    }
//
//    /**
//     * Returns the number of elements in this list.
//     *
//     * @return the number of elements in this list
//     */
//    public int size() {
//	return size;
//    }
//
//    /**
//     * Appends the specified element to the end of this list.
//     *
//     * <p>This method is equivalent to {@link #addLast}.
//     *
//     * @param e element to be appended to this list
//     * @return <tt>true</tt> (as specified by {@link Collection#add})
//     */
//    public boolean add(E e) {
//	addBefore(e, header);
//        return true;
//    }
//
//    /**
//     * Removes the first occurrence of the specified element from this list,
//     * if it is present.  If this list does not contain the element, it is
//     * unchanged.  More formally, removes the element with the lowest index
//     * <tt>i</tt> such that
//     * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt>
//     * (if such an element exists).  Returns <tt>true</tt> if this list
//     * contained the specified element (or equivalently, if this list
//     * changed as a result of the call).
//     *
//     * @param o element to be removed from this list, if present
//     * @return <tt>true</tt> if this list contained the specified element
//     */
//    public boolean remove(Object o) {
//        if (o==null) {
//            for (Entry<E> e = header.next; e != header; e = e.next) {
//                if (e.element==null) {
//                    remove(e);
//                    return true;
//                }
//            }
//        } else {
//            for (Entry<E> e = header.next; e != header; e = e.next) {
//                if (o.equals(e.element)) {
//                    remove(e);
//                    return true;
//                }
//            }
//        }
//        return false;
//    }
//
//    /**
//     * Appends all of the elements in the specified collection to the end of
//     * this list, in the order that they are returned by the specified
//     * collection's iterator.  The behavior of this operation is undefined if
//     * the specified collection is modified while the operation is in
//     * progress.  (Note that this will occur if the specified collection is
//     * this list, and it's nonempty.)
//     *
//     * @param c collection containing elements to be added to this list
//     * @return <tt>true</tt> if this list changed as a result of the call
//     * @throws NullPointerException if the specified collection is null
//     */
//    public boolean addAll(Collection<? extends E> c) {
//        return addAll(size, c);
//    }
//
//    /**
//     * Inserts all of the elements in the specified collection into this
//     * list, starting at the specified position.  Shifts the element
//     * currently at that position (if any) and any subsequent elements to
//     * the right (increases their indices).  The new elements will appear
//     * in the list in the order that they are returned by the
//     * specified collection's iterator.
//     *
//     * @param index index at which to insert the first element
//     *              from the specified collection
//     * @param c collection containing elements to be added to this list
//     * @return <tt>true</tt> if this list changed as a result of the call
//     * @throws IndexOutOfBoundsException {@inheritDoc}
//     * @throws NullPointerException if the specified collection is null
//     */
//    public boolean addAll(int index, Collection<? extends E> c) {
//        if (index < 0 || index > size)
//            throw new IndexOutOfBoundsException("Index: "+index+
//                                                ", Size: "+size);
//        Object[] a = c.toArray();
//        int numNew = a.length;
//        if (numNew==0)
//            return false;
//	modCount++;
//
//        Entry<E> successor = (index==size ? header : entry(index));
//        Entry<E> predecessor = successor.previous;
//	for (int i=0; i<numNew; i++) {
//            Entry<E> e = new Entry<E>((E)a[i], successor, predecessor);
//            predecessor.next = e;
//            predecessor = e;
//        }
//        successor.previous = predecessor;
//
//        size += numNew;
//        return true;
//    }
//
//    /**
//     * Removes all of the elements from this list.
//     */
//    public void clear() {
//        Entry<E> e = header.next;
//        while (e != header) {
//            Entry<E> next = e.next;
//            e.next = e.previous = null;
//            e.element = null;
//            e = next;
//        }
//        header.next = header.previous = header;
//        size = 0;
//	modCount++;
//    }
//
//
//    // Positional Access Operations
//
//    /**
//     * Returns the element at the specified position in this list.
//     *
//     * @param index index of the element to return
//     * @return the element at the specified position in this list
//     * @throws IndexOutOfBoundsException {@inheritDoc}
//     */
//    public E get(int index) {
//        return entry(index).element;
//    }
//
//    /**
//     * Replaces the element at the specified position in this list with the
//     * specified element.
//     *
//     * @param index index of the element to replace
//     * @param element element to be stored at the specified position
//     * @return the element previously at the specified position
//     * @throws IndexOutOfBoundsException {@inheritDoc}
//     */
//    public E set(int index, E element) {
//        Entry<E> e = entry(index);
//        E oldVal = e.element;
//        e.element = element;
//        return oldVal;
//    }
//
//    /**
//     * Inserts the specified element at the specified position in this list.
//     * Shifts the element currently at that position (if any) and any
//     * subsequent elements to the right (adds one to their indices).
//     *
//     * @param index index at which the specified element is to be inserted
//     * @param element element to be inserted
//     * @throws IndexOutOfBoundsException {@inheritDoc}
//     */
//    public void add(int index, E element) {
//        addBefore(element, (index==size ? header : entry(index)));
//    }
//
//    /**
//     * Removes the element at the specified position in this list.  Shifts any
//     * subsequent elements to the left (subtracts one from their indices).
//     * Returns the element that was removed from the list.
//     *
//     * @param index the index of the element to be removed
//     * @return the element previously at the specified position
//     * @throws IndexOutOfBoundsException {@inheritDoc}
//     */
//    public E remove(int index) {
//        return remove(entry(index));
//    }
//
//    /**
//     * Returns the indexed entry.
//     */
//    private Entry<E> entry(int index) {
//        if (index < 0 || index >= size)
//            throw new IndexOutOfBoundsException("Index: "+index+
//                                                ", Size: "+size);
//        Entry<E> e = header;
//        if (index < (size >> 1)) {
//            for (int i = 0; i <= index; i++)
//                e = e.next;
//        } else {
//            for (int i = size; i > index; i--)
//                e = e.previous;
//        }
//        return e;
//    }
//
//
//    // Search Operations
//
//    /**
//     * Returns the index of the first occurrence of the specified element
//     * in this list, or -1 if this list does not contain the element.
//     * More formally, returns the lowest index <tt>i</tt> such that
//     * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt>,
//     * or -1 if there is no such index.
//     *
//     * @param o element to search for
//     * @return the index of the first occurrence of the specified element in
//     *         this list, or -1 if this list does not contain the element
//     */
//    public int indexOf(Object o) {
//        int index = 0;
//        if (o==null) {
//            for (Entry e = header.next; e != header; e = e.next) {
//                if (e.element==null)
//                    return index;
//                index++;
//            }
//        } else {
//            for (Entry e = header.next; e != header; e = e.next) {
//                if (o.equals(e.element))
//                    return index;
//                index++;
//            }
//        }
//        return -1;
//    }
//
//    /**
//     * Returns the index of the last occurrence of the specified element
//     * in this list, or -1 if this list does not contain the element.
//     * More formally, returns the highest index <tt>i</tt> such that
//     * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt>,
//     * or -1 if there is no such index.
//     *
//     * @param o element to search for
//     * @return the index of the last occurrence of the specified element in
//     *         this list, or -1 if this list does not contain the element
//     */
//    public int lastIndexOf(Object o) {
//        int index = size;
//        if (o==null) {
//            for (Entry e = header.previous; e != header; e = e.previous) {
//                index--;
//                if (e.element==null)
//                    return index;
//            }
//        } else {
//            for (Entry e = header.previous; e != header; e = e.previous) {
//                index--;
//                if (o.equals(e.element))
//                    return index;
//            }
//        }
//        return -1;
//    }
//
//    // Queue operations.
//
//    /**
//     * Retrieves, but does not remove, the head (first element) of this list.
//     * @return the head of this list, or <tt>null</tt> if this list is empty
//     * @since 1.5
//     */
//    public E peek() {
//        if (size==0)
//            return null;
//        return getFirst();
//    }
//
//    /**
//     * Retrieves, but does not remove, the head (first element) of this list.
//     * @return the head of this list
//     * @throws NoSuchElementException if this list is empty
//     * @since 1.5
//     */
//    public E element() {
//        return getFirst();
//    }
//
//    /**
//     * Retrieves and removes the head (first element) of this list
//     * @return the head of this list, or <tt>null</tt> if this list is empty
//     * @since 1.5
//     */
//    public E poll() {
//        if (size==0)
//            return null;
//        return removeFirst();
//    }
//
//    /**
//     * Retrieves and removes the head (first element) of this list.
//     *
//     * @return the head of this list
//     * @throws NoSuchElementException if this list is empty
//     * @since 1.5
//     */
//    public E remove() {
//        return removeFirst();
//    }
//
//    /**
//     * Adds the specified element as the tail (last element) of this list.
//     *
//     * @param e the element to add
//     * @return <tt>true</tt> (as specified by {@link Queue#offer})
//     * @since 1.5
//     */
//    public boolean offer(E e) {
//        return add(e);
//    }
//
//    // Deque operations
//    /**
//     * Inserts the specified element at the front of this list.
//     *
//     * @param e the element to insert
//     * @return <tt>true</tt> (as specified by {@link Deque#offerFirst})
//     * @since 1.6
//     */
//    public boolean offerFirst(E e) {
//        addFirst(e);
//        return true;
//    }
//
//    /**
//     * Inserts the specified element at the end of this list.
//     *
//     * @param e the element to insert
//     * @return <tt>true</tt> (as specified by {@link Deque#offerLast})
//     * @since 1.6
//     */
//    public boolean offerLast(E e) {
//        addLast(e);
//        return true;
//    }
//
//    /**
//     * Retrieves, but does not remove, the first element of this list,
//     * or returns <tt>null</tt> if this list is empty.
//     *
//     * @return the first element of this list, or <tt>null</tt>
//     *         if this list is empty
//     * @since 1.6
//     */
//    public E peekFirst() {
//        if (size==0)
//            return null;
//        return getFirst();
//    }
//
//    /**
//     * Retrieves, but does not remove, the last element of this list,
//     * or returns <tt>null</tt> if this list is empty.
//     *
//     * @return the last element of this list, or <tt>null</tt>
//     *         if this list is empty
//     * @since 1.6
//     */
//    public E peekLast() {
//        if (size==0)
//            return null;
//        return getLast();
//    }
//
//    /**
//     * Retrieves and removes the first element of this list,
//     * or returns <tt>null</tt> if this list is empty.
//     *
//     * @return the first element of this list, or <tt>null</tt> if
//     *     this list is empty
//     * @since 1.6
//     */
//    public E pollFirst() {
//        if (size==0)
//            return null;
//        return removeFirst();
//    }
//
//    /**
//     * Retrieves and removes the last element of this list,
//     * or returns <tt>null</tt> if this list is empty.
//     *
//     * @return the last element of this list, or <tt>null</tt> if
//     *     this list is empty
//     * @since 1.6
//     */
//    public E pollLast() {
//        if (size==0)
//            return null;
//        return removeLast();
//    }
//
//    /**
//     * Pushes an element onto the stack represented by this list.  In other
//     * words, inserts the element at the front of this list.
//     *
//     * <p>This method is equivalent to {@link #addFirst}.
//     *
//     * @param e the element to push
//     * @since 1.6
//     */
//    public void push(E e) {
//        addFirst(e);
//    }
//
//    /**
//     * Pops an element from the stack represented by this list.  In other
//     * words, removes and returns the first element of this list.
//     *
//     * <p>This method is equivalent to {@link #removeFirst()}.
//     *
//     * @return the element at the front of this list (which is the top
//     *         of the stack represented by this list)
//     * @throws NoSuchElementException if this list is empty
//     * @since 1.6
//     */
//    public E pop() {
//        return removeFirst();
//    }
//
//    /**
//     * Removes the first occurrence of the specified element in this
//     * list (when traversing the list from head to tail).  If the list
//     * does not contain the element, it is unchanged.
//     *
//     * @param o element to be removed from this list, if present
//     * @return <tt>true</tt> if the list contained the specified element
//     * @since 1.6
//     */
//    public boolean removeFirstOccurrence(Object o) {
//        return remove(o);
//    }
//
//    /**
//     * Removes the last occurrence of the specified element in this
//     * list (when traversing the list from head to tail).  If the list
//     * does not contain the element, it is unchanged.
//     *
//     * @param o element to be removed from this list, if present
//     * @return <tt>true</tt> if the list contained the specified element
//     * @since 1.6
//     */
//    public boolean removeLastOccurrence(Object o) {
//        if (o==null) {
//            for (Entry<E> e = header.previous; e != header; e = e.previous) {
//                if (e.element==null) {
//                    remove(e);
//                    return true;
//                }
//            }
//        } else {
//            for (Entry<E> e = header.previous; e != header; e = e.previous) {
//                if (o.equals(e.element)) {
//                    remove(e);
//                    return true;
//                }
//            }
//        }
//        return false;
//    }
//
//    /**
//     * Returns a list-iterator of the elements in this list (in proper
//     * sequence), starting at the specified position in the list.
//     * Obeys the general contract of <tt>List.listIterator(int)</tt>.<p>
//     *
//     * The list-iterator is <i>fail-fast</i>: if the list is structurally
//     * modified at any time after the Iterator is created, in any way except
//     * through the list-iterator's own <tt>remove</tt> or <tt>add</tt>
//     * methods, the list-iterator will throw a
//     * <tt>ConcurrentModificationException</tt>.  Thus, in the face of
//     * concurrent modification, the iterator fails quickly and cleanly, rather
//     * than risking arbitrary, non-deterministic behavior at an undetermined
//     * time in the future.
//     *
//     * @param index index of the first element to be returned from the
//     *              list-iterator (by a call to <tt>next</tt>)
//     * @return a ListIterator of the elements in this list (in proper
//     *         sequence), starting at the specified position in the list
//     * @throws IndexOutOfBoundsException {@inheritDoc}
//     * @see List#listIterator(int)
//     */
//    public ListIterator<E> listIterator(int index) {
//	return new ListItr(index);
//    }
//
//    private class ListItr implements ListIterator<E> {
//	private Entry<E> lastReturned = header;
//	private Entry<E> next;
//	private int nextIndex;
//	private int expectedModCount = modCount;
//
//	ListItr(int index) {
//	    if (index < 0 || index > size)
//		throw new IndexOutOfBoundsException("Index: "+index+
//						    ", Size: "+size);
//	    if (index < (size >> 1)) {
//		next = header.next;
//		for (nextIndex=0; nextIndex<index; nextIndex++)
//		    next = next.next;
//	    } else {
//		next = header;
//		for (nextIndex=size; nextIndex>index; nextIndex--)
//		    next = next.previous;
//	    }
//	}
//
//	public boolean hasNext() {
//	    return nextIndex != size;
//	}
//
//	public E next() {
//	    checkForComodification();
//	    if (nextIndex == size)
//		throw new NoSuchElementException();
//
//	    lastReturned = next;
//	    next = next.next;
//	    nextIndex++;
//	    return lastReturned.element;
//	}
//
//	public boolean hasPrevious() {
//	    return nextIndex != 0;
//	}
//
//	public E previous() {
//	    if (nextIndex == 0)
//		throw new NoSuchElementException();
//
//	    lastReturned = next = next.previous;
//	    nextIndex--;
//	    checkForComodification();
//	    return lastReturned.element;
//	}
//
//	public int nextIndex() {
//	    return nextIndex;
//	}
//
//	public int previousIndex() {
//	    return nextIndex-1;
//	}
//
//	public void remove() {
//            checkForComodification();
//            Entry<E> lastNext = lastReturned.next;
//            try {
//                LinkedList.this.remove(lastReturned);
//            } catch (NoSuchElementException e) {
//                throw new IllegalStateException();
//            }
//	    if (next==lastReturned)
//                next = lastNext;
//            else
//		nextIndex--;
//	    lastReturned = header;
//	    expectedModCount++;
//	}
//
//	public void set(E e) {
//	    if (lastReturned == header)
//		throw new IllegalStateException();
//	    checkForComodification();
//	    lastReturned.element = e;
//	}
//
//	public void add(E e) {
//	    checkForComodification();
//	    lastReturned = header;
//	    addBefore(e, next);
//	    nextIndex++;
//	    expectedModCount++;
//	}
//
//	final void checkForComodification() {
//	    if (modCount != expectedModCount)
//		throw new ConcurrentModificationException();
//	}
//    }
//
//    private static class Entry<E> {
//	E element;
//	Entry<E> next;
//	Entry<E> previous;
//
//	Entry(E element, Entry<E> next, Entry<E> previous) {
//	    this.element = element;
//	    this.next = next;
//	    this.previous = previous;
//	}
//    }
//
//    private Entry<E> addBefore(E e, Entry<E> entry) {
//	Entry<E> newEntry = new Entry<E>(e, entry, entry.previous);
//	newEntry.previous.next = newEntry;
//	newEntry.next.previous = newEntry;
//	size++;
//	modCount++;
//	return newEntry;
//    }
//
//    private E remove(Entry<E> e) {
//	if (e == header)
//	    throw new NoSuchElementException();
//
//        E result = e.element;
//	e.previous.next = e.next;
//	e.next.previous = e.previous;
//        e.next = e.previous = null;
//        e.element = null;
//	size--;
//	modCount++;
//        return result;
//    }
//
//    /**
//     * @since 1.6
//     */
//    public Iterator<E> descendingIterator() {
//        return new DescendingIterator();
//    }
//
//    /** Adapter to provide descending iterators via ListItr.previous */
//    private class DescendingIterator implements Iterator {
//        final ListItr itr = new ListItr(size());
//	public boolean hasNext() {
//	    return itr.hasPrevious();
//	}
//	public E next() {
//            return itr.previous();
//        }
//	public void remove() {
//            itr.remove();
//        }
//    }
//
//    /**
//     * Returns a shallow copy of this <tt>LinkedList</tt>. (The elements
//     * themselves are not cloned.)
//     *
//     * @return a shallow copy of this <tt>LinkedList</tt> instance
//     */
//    public Object clone() {
//        LinkedList<E> clone = null;
//	try {
//	    clone = (LinkedList<E>) super.clone();
//	} catch (CloneNotSupportedException e) {
//	    throw new InternalError();
//	}
//
//        // Put clone into "virgin" state
//        clone.header = new Entry<E>(null, null, null);
//        clone.header.next = clone.header.previous = clone.header;
//        clone.size = 0;
//        clone.modCount = 0;
//
//        // Initialize clone with our elements
//        for (Entry<E> e = header.next; e != header; e = e.next)
//            clone.add(e.element);
//
//        return clone;
//    }
//
//    /**
//     * Returns an array containing all of the elements in this list
//     * in proper sequence (from first to last element).
//     *
//     * <p>The returned array will be "safe" in that no references to it are
//     * maintained by this list.  (In other words, this method must allocate
//     * a new array).  The caller is thus free to modify the returned array.
//     *
//     * <p>This method acts as bridge between array-based and collection-based
//     * APIs.
//     *
//     * @return an array containing all of the elements in this list
//     *         in proper sequence
//     */
//    public Object[] toArray() {
//	Object[] result = new Object[size];
//        int i = 0;
//        for (Entry<E> e = header.next; e != header; e = e.next)
//            result[i++] = e.element;
//	return result;
//    }
//
//    /**
//     * Returns an array containing all of the elements in this list in
//     * proper sequence (from first to last element); the runtime type of
//     * the returned array is that of the specified array.  If the list fits
//     * in the specified array, it is returned therein.  Otherwise, a new
//     * array is allocated with the runtime type of the specified array and
//     * the size of this list.
//     *
//     * <p>If the list fits in the specified array with room to spare (i.e.,
//     * the array has more elements than the list), the element in the array
//     * immediately following the end of the list is set to <tt>null</tt>.
//     * (This is useful in determining the length of the list <i>only</i> if
//     * the caller knows that the list does not contain any null elements.)
//     *
//     * <p>Like the {@link #toArray()} method, this method acts as bridge between
//     * array-based and collection-based APIs.  Further, this method allows
//     * precise control over the runtime type of the output array, and may,
//     * under certain circumstances, be used to save allocation costs.
//     *
//     * <p>Suppose <tt>x</tt> is a list known to contain only strings.
//     * The following code can be used to dump the list into a newly
//     * allocated array of <tt>String</tt>:
//     *
//     * <pre>
//     *     String[] y = x.toArray(new String[0]);</pre>
//     *
//     * Note that <tt>toArray(new Object[0])</tt> is identical in function to
//     * <tt>toArray()</tt>.
//     *
//     * @param a the array into which the elements of the list are to
//     *          be stored, if it is big enough; otherwise, a new array of the
//     *          same runtime type is allocated for this purpose.
//     * @return an array containing the elements of the list
//     * @throws ArrayStoreException if the runtime type of the specified array
//     *         is not a supertype of the runtime type of every element in
//     *         this list
//     * @throws NullPointerException if the specified array is null
//     */
//    public <T> T[] toArray(T[] a) {
//        if (a.length < size)
//            a = (T[])java.lang.reflect.Array.newInstance(
//                                a.getClass().getComponentType(), size);
//        int i = 0;
//	Object[] result = a;
//        for (Entry<E> e = header.next; e != header; e = e.next)
//            result[i++] = e.element;
//
//        if (a.length > size)
//            a[size] = null;
//
//        return a;
//    }
//
//    private static final long serialVersionUID = 876323262645176354L;
//
//    /**
//     * Save the state of this <tt>LinkedList</tt> instance to a stream (that
//     * is, serialize it).
//     *
//     * @serialData The size of the list (the number of elements it
//     *             contains) is emitted (int), followed by all of its
//     *             elements (each an Object) in the proper order.
//     */
//    private void writeObject(java.io.ObjectOutputStream s)
//        throws java.io.IOException {
//	// Write out any hidden serialization magic
//	s.defaultWriteObject();
//
//        // Write out size
//        s.writeInt(size);
//
//	// Write out all elements in the proper order.
//        for (Entry e = header.next; e != header; e = e.next)
//            s.writeObject(e.element);
//    }
//
//    /**
//     * Reconstitute this <tt>LinkedList</tt> instance from a stream (that is
//     * deserialize it).
//     */
//    private void readObject(java.io.ObjectInputStream s)
//        throws java.io.IOException, ClassNotFoundException {
//	// Read in any hidden serialization magic
//	s.defaultReadObject();
//
//        // Read in size
//        int size = s.readInt();
//
//        // Initialize header
//        header = new Entry<E>(null, null, null);
//        header.next = header.previous = header;
//
//	// Read in all elements in the proper order.
//	for (int i=0; i<size; i++)
//            addBefore((E)s.readObject(), header);
//    }
//}
